Born in Krugersdorp, Kleyn is a tall robust lock. He moved to Cape Town to study at Stellenbosch University where he made it into the Western Province set up where he won the U19 & U21 Currie Cups.
After a number of injuries he went on to play a vital role in the WP winning Currie Cup side in 2014. Since then, he has played over 15 Super Rugby games for the Stormers.
In July 2016, Western Province Rugby opted to release Kleyn from his contract in order for him to join Irish team Munster after the 2016 Super Rugby competition.
Jean joined the province on a three-year contract at the start of the 2016/17 season.
After 42 appearances and 6 tries scored for Munster, the South African lock signed a new deal that would keep him at the province until June 2022.
The new deal means Kleyn becomes eligible to represent Ireland under World Rugby residency rules in September 2019
As of the 2018/2019 Champions Cup, Kleyn has had 11 Champions Cup appearances scoring 1 try and 5 points.
In May 2019, he was named in Ireland's squad for the 2019 Rugby World Cup pre-season, with Ireland confirming he will qualify on August 8th and will be able to play in all of the warm-up games.
(LS May 28, 2019)
No 5 Lock
|2016 - present|
No 5 Lock
|2014 - 2016|
|2014 - 2017|
No 4 Lock
|2019 - 2020|